Moisture problem

[Happymi]

We are in freezing temps. with our heat on. We close up tight at night and when we wake up I have water inside the windows and front windshield. This morning one of the windows was frozen.

I have read where people have said to leave a vent open or a window cracked. Does this really work for you? I would think you would lose too much heat.

I just soak it up with a towel but I am afraid that there might be damage happening behind the walls.

I also read about a dehumidifier but I don't know about that.

Happymi

[Happymi]

We are in freezing temps. with our heat on. We close up tight at night and when we wake up I have water inside the windows and front windshield. This morning one of the windows was frozen.

I have read where people have said to leave a vent open or a window cracked. Does this really work for you? I would think you would lose too much heat.

I just soak it up with a towel but I am afraid that there might be damage happening behind the walls.

I also read about a dehumidifier but I don't know about that.

Happymi

[Latitude]

Happy

Set a fan up so it blows the air around. If you have the front night shades pulled you will need to open them some so as to get the air moving over the glass.

Rick

[GaryKD]

Hi Happy,
If your windows have weep holes, make sure the tracks and the holes are clear of debris. If the weep track and holes are working, there will be no damage inside the walls.

[Spikester]

We do leave a ceiling vent ever so slightly cracked open at night. Not sure of your front shade/privacy shade configuration, our shade, when down, leaves a space of approx 10" between it and the windshield. At night we place a small ceramic heater, in the fan only mod, in this void area, keeps the condensation from building on the windshield.

When parked in cold weather during the day, leave the ceramic heater on the dash pointed at the front windshield in the heat mode. Does away with the cold draft radiating through the front windshield, therefore motorhome stays a lot warmer.

Spike

[RVDude]

You hit one of the major drawbacks to propane heat. That LPG furnace burns a lot of LPG on a cold night and guess what is one of the major byproducts of LPG combustion? Besides CO2 the other biggie is H20, yep water! Hence, propane heaters will create a large amount of moisture. Nothing you can do in a tight RV space except provide some venting or offload as much heating as you can to electric.
Here's the reaction... Propane + Oxygen ? Carbon Dioxide + Water

[DavidMc]

I think that what RVDude mentioned about water produced by propane heaters applies (as an inside issue) to just the UNVENTED versions.

Most built-in RV propane furnaces vent to the outside (and even get their combustion air from the outside).

Somewhere along the line you need to give up some heat to keep dry. You breathe, you wash, you cook, you dry towels -- and you add moisture to the air inside the RV.

Open a vent about half-an-inch, let the small kitchen stove vent remain open -- that might be enough. This is a try-and-try-again effort until you find the balance point for your RV and life-pattern.

[Happymi]

Thank You ALL

We are not using propane. We are using Hydro Heat which is working very well for us.

I am going to try everything all of you have recommended. I didn't know how open we should leave the vent until you gave me the info.

Isn't this a great place to go to when needed. I love iRV2.com.

Happymi

[TXiceman]

A working RV furnace is an indirect heat for the RV. The propane is burned in a heat exchanger that gets it air fromt he outside and exhaust it to the outside. The inside air is blown across the hot surface of the heat exchanger. Therefore there is no moisture added to the inside air from the propane conbustion. All of the CO2, water vapor and minute portions of CO are vented outside and never comes in contact witht he inside air.

If your heat exchanger is cracked or rusted through, you can get some combustion gases coming into the conditioned space of the coach which is very dangerous.

As for leaving a vent open at night, it depends on the number of peole and pets in the RV plus the size of the RV. The more people and the smaller the RV, the more you have to have it open. We ususlly leave the bedroom or bath vent cracked open just enough that you can see that it is open...maybe 1/4" to 1/2".

If you are in freezing temperatures, I am surprised that the heat pump operates very well. The colder is is outside, the less effectively the heat pump will operate. Most of them swith to auxlliary heat mode well before you reach freezing temperatures.

You need to keep the moisture under control in an RV. If you are getting it to condense on the windows, it is probably getting into the walls as well. The moisture will drive from the highest moisture content to the lower moisture content and lower temperature. You will ahve a temperature gradient across the wall ranging from basically the interior temperature tot he utside temperature. Somewhere in the wall, the temperature will be below the dewpoint of the air in the wall and the water vapor will condense. That is why vapor barriers are so important in buildings. There is a difference where the vapor barrier is applied between up north and down south.
Ken